A Universal Planetary Substorm Model

太阳不断地向太空发射一股带电粒子流，被称为太阳风。这种风，以100秒到1000公里/S的速度传播，在整个太阳系中传播，所有的行星都绕太阳运行。像地球这样的行星不会受到太阳风的威胁，因为它所包含的带电粒子受到内部产生的强大磁场的阻碍，无法撞击表面。如果没有这个场，太阳风将剥离大气层，对生命细胞造成巨大破坏，使我们所理解的宏观生命变得不可能。虽然表面受到了保护，但太阳风确实有重要的影响，其中最大的影响是地球磁场的扭曲，在太阳风的上游侧变得压缩，在下游侧拉伸成一条长长的“磁尾”。这个磁尾从月球轨道延伸到地球本身半径的1000多倍的距离。磁尾中的事件被称为“亚暴”，加速粒子从太空进入地球上层大气层，在那里它们有许多影响，其中最壮观的是触发了北极光和南极光。还有许多技术影响，包括充电和近地轨道航天器阻力增加，这可能导致卫星运行寿命缩短。亚暴可以被描述为一种简单的电路，在磁尾有一个发电机，高层大气中的一个电阻通过磁力线的“导线”连接起来，但是这个电路的影响是不容易预测的，因为发电机不会产生稳定的电流。相反，电流的变化取决于太阳风的“天气条件”，太阳风为电路提供能源。水星、土星和木星的磁尾形状与地球相似，也会经历亚暴。在水星，亚暴电路发电机是由太阳风驱动的，就像在地球上一样，但在土星和木星上，发电机还有另一种能源--行星自身的快速自转。木星的亚暴电路发生器是由这种旋转能源主导的，但仍然受到太阳风的影响。在土星，亚暴发电机的能量是由旋转和太阳风输入提供的。这个项目的目的是为任何磁尾与地球或木星相似的行星建立亚暴电路模型，目的是了解亚暴存在的情况，当它们以可预测的、周期性的方式发生，当它们在太阳风和旋转源的能量输入方面表现出混乱、不可预测的行为时。这将允许对预测亚暴电路的影响的时间尺度设置限制，以与可以计算天气预报的有用时间尺度的限制相同的方式。因为该模型将不限于任何一组行星特征(特别是旋转速度、磁场强度和轨道距离)或特定的太阳风条件集合，它将不仅限于一颗行星，而是可以用于任何像地球一样有磁尾的行星。这意味着它可以用来预测太阳系外的行星，这反过来可以用来帮助从保护表面免受恒星风粒子影响的角度来理解这些行星的宜居性。

The sun continuously emits a stream of electrically charged particles, known as the solar wind, into space. This wind, travelling at 100s to 1000s km/s, propagates throughout the solar system and all the planets move through it as they orbit the sun. Planets like the Earth are protected from the dangers of the solar wind since the charged particles that it consists of are hindered from striking the surface by a strong internally generated magnetic field. Without this field, the solar wind would strip away the atmosphere and cause enormous damage to living cells, making macroscopic life as we understand it impossible. Although the surface is protected, the solar wind does have important effects, the largest of which is the distortion of Earth's magnetic field, which becomes compressed on the up-stream side of the solar wind and stretched into a long "magnetotail" on the down-stream side. This magnetotail extends beyond the orbit of the moon to a distance over 1,000 times the radius of Earth itself. Events in the magnetotail known as "substorms" accelerate particles from space into Earth's upper atmosphere where they have numerous impacts, the most spectacular of which is the triggering of the Aurora Borealis and Aurora Australis. There are also numerous technological impacts, including electrical charging and increased drag on spacecraft in Low Earth Orbit, which can lead to reduced operational lifetime of the satellites. Substorms can be described as a simple electrical circuit with a generator in the magnetotail and a resistor in the upper atmosphere linked by "wires" following lines of magnetic force, however the effects of this circuit are not easily predictable because the generator is not creating a steady current. Instead the current varies depending on the "weather conditions" of the solar wind, which provides the energy source for the circuit.Mercury, Saturn and Jupiter have magnetotails similar in form to that of Earth and also experience substorms. At Mercury the substorm circuit generator is driven by the solar wind, as it is at Earth but at Saturn and Jupiter there is another source of energy for the generator - the planets' own rapid rotation. Jupiter's substorm circuit generator is dominated by this rotational energy source but is still influenced by the solar wind. At Saturn the substorm generator's energy is supplied in significant amounts by both rotational and solar wind inputs.The aim of this project is to model the substorm electrical circuit for any planet with a magnetotail similar to that of Earth or Jupiter with the intent of understanding the circumstances when substorms are present, when they occur in a predictable, periodic fashion and when they exhibit chaotic, unpredictable behaviour in terms of the energy input from the solar wind and rotational sources. This will allow limits to be placed on the timescale that forecasting of the effects of the substorm circuit is possible for, in the same way that limits can be calculated for the useful timescale of a weather forecast.Because the model will not be limited to any one set of planetary characteristics (particularly rotational speed, magnetic field strength and orbital distance) or specific set of solar wind conditions, it will not be limited to just one planet but instead can be used for any planet with a magnetotail like Earth's. This means it can be used to make predictions about planets outside the solar system which in turn can be used to help understand the habitability of these planets of from the perspective of protection of the surface from stellar wind particles.